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-rw-r--r--src/semantic/analysis.rs248
1 files changed, 248 insertions, 0 deletions
diff --git a/src/semantic/analysis.rs b/src/semantic/analysis.rs
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+// Copyright ⓒ 2017 David Li.
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+use ::ast::{self, WithLocation};
+use super::environment;
+use super::types::{self, Ty};
+
+#[derive(Debug)]
+pub enum TypeError {
+ Unimplemented,
+ LengthMismatch {
+ expected: usize,
+ actual: usize,
+ },
+ Mismatch {
+ expected: Ty,
+ actual: Ty,
+ },
+ UnboundName,
+}
+
+type TypeEnvironment<'a> = environment::Environment<'a, String, Ty>;
+pub type Result = ::std::result::Result<Ty, WithLocation<TypeError>>;
+
+pub fn translate(program: &ast::Program) -> Result {
+ let mut venv = TypeEnvironment::new(None);
+ let mut tenv = TypeEnvironment::new(None);
+ tenv.add_binding("int".into(), Ty::Int);
+ tenv.add_binding("string".into(), Ty::String);
+ trans_exp(&mut venv, &mut tenv, &*program.0)
+}
+
+macro_rules! err {
+ ($exp: expr, $err: expr) => {
+ Err(WithLocation::new($err, $exp.start, $exp.end))
+ }
+}
+
+fn trans_ty<'a>(
+ venv: &mut TypeEnvironment<'a>,
+ tenv: &mut TypeEnvironment<'a>,
+ ty: &WithLocation<ast::Ty>) -> Result {
+ match ty.value {
+ ast::Ty::Name(ref name) => {
+ tenv.lookup(&name)
+ .map(|v| v.clone())
+ .ok_or(WithLocation::new(TypeError::UnboundName, ty.start, ty.end))
+ }
+ ast::Ty::Array(ref inner_ty) => {
+ trans_ty(venv, tenv, &inner_ty)
+ },
+ ast::Ty::Record(ref fields) => {
+ let mut result = vec![];
+ for field in fields {
+ result.push(types::RecordField::new(
+ field.name.clone(),
+ trans_ty(venv, tenv, &field.ty)?));
+ }
+ Ok(Ty::Record(result))
+ },
+ }
+}
+
+fn trans_decl<'a>(
+ venv: &mut TypeEnvironment<'a>,
+ tenv: &mut TypeEnvironment<'a>,
+ decl: &WithLocation<ast::Declaration>) -> Result {
+ match decl.declaration {
+ ast::DeclarationBody::Fun { ref ty, ref params, ref body } => {
+ let declared_ty = if let &Some(ref ty) = ty {
+ Some(ast::WithLocation::new(trans_ty(venv, tenv, &ty)?, ty.start, ty.end))
+ } else { None };
+
+ let mut new_venv = TypeEnvironment::new(Some(venv));
+ let mut new_tenv = TypeEnvironment::new(Some(tenv));
+ let mut arg_types = vec![];
+ for param in params.iter() {
+ let arg_ty = trans_ty(&mut new_venv, &mut new_tenv, &param.ty)?;
+ arg_types.push(arg_ty.clone());
+ new_venv.add_binding(param.name.value.clone(), arg_ty);
+ }
+
+ let body_ty = trans_exp(&mut new_venv, &mut new_tenv, &*body)?;
+
+ if let Some(decl_ty) = declared_ty {
+ if &decl_ty.value != &body_ty {
+ return err!(decl_ty, TypeError::Mismatch {
+ expected: decl_ty.value,
+ actual: body_ty,
+ });
+ }
+ }
+
+ Ok(Ty::Function(arg_types, Box::new(body_ty)))
+ }
+ ast::DeclarationBody::Ty { ref ty } => {
+ trans_ty(venv, tenv, ty)
+ }
+ ast::DeclarationBody::Var { ref ty, ref value } => {
+ let actual_ty = trans_exp(venv, tenv, &value)?;
+ if let &Some(ref ty) = ty {
+ let decl_ty = trans_ty(venv, tenv, &ty)?;
+ if decl_ty != actual_ty {
+ return err!(ty, TypeError::Mismatch {
+ expected: decl_ty,
+ actual: actual_ty,
+ });
+ }
+ }
+ Ok(actual_ty)
+ }
+ }
+}
+
+fn trans_exp<'a>(
+ venv: &mut TypeEnvironment<'a>,
+ tenv: &mut TypeEnvironment<'a>,
+ exp: &WithLocation<ast::Expression>) -> Result {
+ use ast::Expression::*;
+
+ match &exp.value {
+ &Let(ref decls, ref body) => {
+ let mut new_venv = TypeEnvironment::new(Some(venv));
+ let mut new_tenv = TypeEnvironment::new(Some(tenv));
+ for decl in decls.iter() {
+ let decl_ty = trans_decl(&mut new_venv, &mut new_tenv, decl)?;
+ match decl.declaration {
+ ast::DeclarationBody::Fun { .. } | ast::DeclarationBody::Var { .. } => {
+ new_venv.add_binding(decl.name.clone(), decl_ty);
+ }
+ ast::DeclarationBody::Ty { .. } => {
+ new_tenv.add_binding(decl.name.clone(), decl_ty);
+ }
+ }
+ }
+ trans_exp(&mut new_venv, &mut new_tenv, &*body)
+ },
+ &Call(ref name, ref args) => {
+ let mut arg_types = vec![];
+ for arg in args {
+ arg_types.push(trans_exp(venv, tenv, arg)?);
+ }
+
+ let fun_ty = venv.lookup(name)
+ .ok_or(WithLocation::new(TypeError::UnboundName,
+ exp.start, exp.end))?;
+ match fun_ty {
+ &Ty::Function(ref expected_args, ref result) => {
+ if expected_args.len() != arg_types.len() {
+ return err!(exp, TypeError::LengthMismatch {
+ expected: expected_args.len(),
+ actual: arg_types.len(),
+ });
+ }
+ for (i, (provided_ty, expected_ty)) in
+ arg_types.iter().zip(expected_args).enumerate() {
+ if provided_ty != expected_ty {
+ return err!(args[i], TypeError::Mismatch {
+ expected: expected_ty.clone(),
+ actual: provided_ty.clone(),
+ })
+ }
+ }
+ Ok((**result).clone())
+ },
+ otherwise => {
+ err!(exp, TypeError::Mismatch {
+ // TODO: better way to handle this
+ expected: Ty::Function(arg_types, Box::new(Ty::Nil)),
+ actual: otherwise.clone(),
+ })
+ }
+ }
+ },
+ &UnaryOp(ref op, ref operand) => {
+ use ast::UnaryOp::*;
+ let operand_ty = trans_exp(venv, tenv, operand)?;
+ match op {
+ &Neg | &Pos => {
+ match operand_ty {
+ Ty::Int => {
+ Ok(Ty::Int)
+ }
+ other => {
+ err!(operand, TypeError::Mismatch {
+ expected: Ty::Int,
+ actual: other,
+ })
+ }
+ }
+ }
+ &Not => {
+ err!(exp, TypeError::Unimplemented)
+ }
+ }
+ },
+ &BinOp(ref op, ref left, ref right) => {
+ use ast::BinOp::*;
+ let left_ty = trans_exp(venv, tenv, left)?;
+ let right_ty = trans_exp(venv, tenv, right)?;
+ match op {
+ &Add => {
+ match (left_ty, right_ty) {
+ (Ty::Int, Ty::Int) => {
+ Ok(Ty::Int)
+ }
+ (Ty::String, Ty::String) => {
+ Ok(Ty::String)
+ }
+ (Ty::Int, other) | (other, Ty::Int) => {
+ err!(right, TypeError::Mismatch {
+ expected: Ty::Int,
+ actual: other,
+ })
+ }
+ (Ty::String, other) | (other, Ty::String) => {
+ err!(right, TypeError::Mismatch {
+ expected: Ty::String,
+ actual: other,
+ })
+ }
+ _ => {
+ err!(exp, TypeError::Unimplemented)
+ }
+ }
+ }
+ _ => {
+ err!(exp, TypeError::Unimplemented)
+ }
+ }
+ },
+ &Number(_) => Ok(Ty::Int),
+ &String(_) => Ok(Ty::String),
+ &Name(ref name) => {
+ if let Some(ty) = venv.lookup(name) {
+ Ok(ty.clone())
+ }
+ else {
+ err!(exp, TypeError::UnboundName)
+ }
+ },
+ &Nil => {
+ Err(WithLocation::new(TypeError::Unimplemented, exp.start, exp.end))
+ },
+ }
+}